Electric power steering apparatus

a technology of electric power steering and steering wheel, which is applied in the direction of electric steering, power driven steering, vehicle components, etc., can solve the problems of increasing manufacturing costs, unable to detect the absolute steering position of the steering wheel only by using a single rotation angle sensor, and inability to control the steering wheel of a vehicl
US7325646B2Inactive Publication Date: 2008-02-05JTEKT CORP
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Patents(United States)
Current Assignee / Owner
JTEKT CORP
Publication Date
2008-02-05
Estimated Expiration
Not applicable · inactive patent

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Abstract

In an electric power steering apparatus, at least one of a speed reduction gear ratio of the speed reduction gear mechanism and the number of pole pairs of a motor resolver is set in such a manner that a calculated value, which is obtained by multiplying the speed reduction gear ratio of the speed reduction gear mechanism with the number of pole pairs of the motor resolver, represents a non-integer having a numerical value of the decimal place. This electric power steering apparatus includes an absolute rotational position specifying device configured to specify an absolute rotational position of the steering wheel from among plural possible absolute rotational positions that are obtained based on the steering angle and the motor electrical angle. This electric power steering apparatus is hence capable of controlling an electric motor based on the absolute rotational position of the steering wheel.
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Description

FIELD OF THE INVENTION

[0001] This invention relates to an electric power steering apparatus.BACKGROUND

[0002] There is a conventionally known electric power steering apparatus, according to which an extent of a steering force needed for operating a steering wheel can be reduced by applying an assist force by a motor to a steering mechanism connected to a steering shaft. In this type of electric power steering apparatus, a steering wheel is rotated, within a limited rotational range, more than one turn (cf. one turn is 360 degrees) in a clockwise direction and more than one turn (cf. one turn is 360 degrees) in a counterclockwise direction. When a vehicle runs straight ahead, the steering wheel is defined to be positioned at a neutral steering position. A steering angle of the steering wheel is grasped by detecting, as an absolute steering position, a rotational position of the steering wheel on a basis of a degree of angle from this neutral steering position.

[0003] The aforementioned st...

Claims

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